W100 · Stage 2 of 4

W100 Multimedia Filter

The second stage — a graded bed of anthracite, sand and gravel that strips the fine suspended solids and turbidity the separator leaves behind. Capacities from 2,000 to 100,000 litres per hour.

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KKE W100 multimedia filter, 2,000 litres per hour — FRP pressure vessel with multiport control valve

Free tool

Size your water-recycling system in minutes

Tell us what you wash and the tool returns your treatment capacity, the exact W100 skids you need, tank volumes and the freshwater you'll save — with the annual saving in your local currency.

Open the sizing tool

90%

less freshwater

2 min

to a full estimate

Why it's required

Separated water is not yet reusable water

Stage 1 takes out the free oil, the grease and the heavy sludge. What leaves it still carries everything a wash bay generates that is too fine to settle and too small to skim — silt and clay off wheel arches and chassis, road dust, brake and tyre dust, fine sand. Those particles stay in suspension and travel with the water wherever you send it. Stage 2 is where they come out.

The wash result

Cloudy water shows on the vehicle

Suspended solids do not rinse away. They dry on the surface you have just cleaned.

A fine film and spotting on paint and glass, worst on dark vehicles
Grit carried back onto a panel that was already clean
Nozzles blocking, so the spray pattern goes patchy and the wash misses areas

The machinery

Fine grit wears out the expensive parts

Abrasive solids pass straight through every component downstream of the filter you did not install.

High-pressure pump seals, plungers and valves wear early
Nozzle orifices wear open — pressure and impact drop off wash by wash
Strainers, small orifices and spray bars clog and need manual cleaning

The rest of the loop

It protects the two stages behind it

Carbon and resin work by surface contact. Feed them turbid water and you pay for it in media.

Activated carbon (Stage 3) blinds and channels, losing adsorption capacity early
Softener resin (Stage 4) fouls and loses exchange capacity
Solids you do not remove settle in the recycle tanks as sludge, and turn odorous
Suspended solids are a regulated parameter — any overflow or blowdown still has to meet the limit

Labelled cutaway of the KKE W100 multimedia filter: multiport control valve, upper distributor, freeboard, and the graded bed of anthracite, fine silica sand, coarse silica sand, fine gravel and coarse gravel above the bottom laterals — In service, water travels down through the graded bed; the slotted bottom laterals collect it and the central riser returns it to the valve outlet. The empty freeboard above the bed is the room the media needs to lift into during backwash.

How it works

The service cycle

Filtration is a single downward pass through the media bed, driven by the skid's own circulation pump. A coagulant is dosed at the inlet; from there everything that happens is physical.

Coagulant dosed at the inlet

Before water reaches the vessel, an automatic dosing pump adds a measured coagulant. It strips the surface charge that keeps the finest particles apart, so they agglomerate into flocs large enough for the bed to catch. Without that step the ultrafines that make recycled water look grey would pass straight through any sand bed.

In through the valve, spread across the bed

Water enters through the multiport control valve and drops into the upper distributor. The diffuser basket spreads the flow across the full area of the bed, so the incoming stream cannot cut a channel through the top layer and short-circuit the media.

Held through the depth of the bed

The filtering layers are graded coarse-to-fine in the direction of flow: coarse, low-density anthracite on top, fine silica sand beneath it. This is depth filtration, not a screen — the larger flocs strain out at the surface of the anthracite and the rest are intercepted and held on grain surfaces all the way down. Storing the load through the depth instead of caking it on top is what makes the runs between backwashes long.

Collected and returned

Below the filtering layers sit coarse silica sand, fine gravel and coarse gravel — a support bed that holds the fine sand up and spreads backwash flow evenly. The slotted laterals bedded in it collect the filtered water and send it up the central riser tube to the valve outlet: on to the activated-carbon filter, or straight back to the wash.

Cutaway of the KKE W100 multimedia filter showing the graded media bed, central riser tube and bottom laterals inside the FRP vessel

How it works

Backwash: the bed cleans itself

As solids accumulate, the pressure drop across the bed rises. That rising differential — or a set interval on an automatic system — is the signal to backwash. Nothing is replaced and nothing is dosed into the cycle: the bed is cleaned by the filter's own filtered water, run the other way.

A cycle takes a few minutes, and the W100's built-in controls sequence it, so it can run outside wash hours without an operator.

Backwash — the valve reverses the flow: down the riser, out through the laterals and up through the bed. The media lifts and fluidises into the freeboard, grains scour against one another, and the released dirt leaves through the valve's waste port to your sludge line.
Rinse — flow returns downward until it runs clear, settling the bed back down.
It re-stratifies on its own — anthracite is roughly half as dense as silica sand, so the heavy fine sand settles first and the light coarse anthracite last. The graded bed rebuilds itself in the right order every single time.
Back to service — the pressure drop returns to its clean-bed value and the next run begins. Watch that one reading for a few weeks and it will tell you your real backwash interval better than any table.

Why three media, not just sand

A bed of one uniform sand grade behaves like a screen. Nearly everything is caught in the top few millimetres, that layer cakes over, the pressure drop climbs quickly, and you are backwashing again long before the depth below has done any work.

Grading the bed spreads the load instead of concentrating it. Coarse, light anthracite on top takes the bulk of the solids, the fine silica sand beneath it does the polishing, and the coarse sand and graded gravel below support the bed and keep media out of the laterals. The same vessel therefore holds far more dirt before it needs cleaning — longer runs, fewer backwashes, less water sent to sludge, and clearer water leaving.

The layers keep their order because their densities differ. Anthracite is roughly half as dense as silica sand, so however hard the bed is fluidised during a backwash, it always settles back coarse-over-fine. That is the whole reason a multimedia bed still performs like a new one after hundreds of cycles.

At a glance

Key features

Three-layer media bed

Anthracite, sand and gravel, graded for high dirt-holding and long runs.

Removes fine solids

Cuts turbidity and suspended particles down to a low, consistent level.

Long filtration cycles

High dirt-holding capacity means fewer backwashes and less downtime.

Automatic backwash

A self-cleaning cycle restores the bed with minimal operator input.

Skid-mounted

Compact and plug-and-play; connects in-line after the oil–sludge separator.

Corrosion-resistant

FRP filament-wound vessel — nothing in it to rust, built for continuous wet-service duty.

Specifications

Capacities & configuration

Specification	Detail
Stage	2 of 4 — filtration
Flow rates	2,000 to 100,000 litres per hour
Inlet turbidity	50–100 NTU raw water
Filtration principle	Depth filtration through a graded media bed
Pre-treatment	Automatic coagulant dosing at the inlet
Filtering media	Anthracite over fine silica sand
Support bed	Coarse silica sand · fine gravel · coarse gravel
Vessel	FRP filament-wound pressure vessel
Plumbing	PVC — rust-proof
Control valve	Multiport — service / backwash / rinse
Cleaning	Automatic backwash and rinse
Controls	Fully automatic, built into the skid
Connects after	Oil–sludge separator (Stage 1)
Feeds	Activated-carbon filter (Stage 3)

Questions we get

Multimedia filter — common questions

How often does it need backwashing?

It depends on how much solid your water carries and how hard the filter is worked, so the honest answer is that the pressure drop across the bed tells you — not the calendar. Dirtier duty (construction plant, mining vehicles, tipper fleets) loads a bed far faster than passenger-car washing at the same flow. On an automatic W100 the controller runs the cycle on a set interval, and we set that interval from your own readings at commissioning.

Does it use chemicals or consumables?

One chemical: a coagulant, dosed automatically at the inlet ahead of the vessel, which clumps the finest particles into flocs the bed can actually catch. The filtration itself is purely physical, and the backwash uses nothing but the filter's own filtered water. Beyond coagulant, the only consumable is the media — a periodic top-up rather than a running cost.

How dirty can the water going in be?

The unit is built for raw water in the 50–100 NTU turbidity band, which covers most commercial and industrial wash duty, and it removes turbidity up to that ceiling. If your water is consistently dirtier than that, the answer is usually more settling volume or a larger Stage 1 rather than a larger filter — tell us what you wash and we will size the front of the loop properly.

How long does the media last?

Anthracite and silica sand are graded mineral media, so they wear slowly and are normally topped up rather than replaced wholesale; the gravel support bed usually stays put for the life of the vessel. Actual life depends on your solids load and on how well Stage 1 is keeping oil off the bed. We confirm the media schedule for your configuration with the quotation.

Can I run the filter without the oil–sludge separator?

We would not recommend it. Free oil coats media grains and blinds the bed, and an oil-fouled bed cannot be backwashed clean — you end up changing media instead of cleaning it. Stage 1 exists to keep oil and heavy sludge off the filter, which is why the two are specified together.

Does it soften the water or take the smell out?

No, and it is not meant to. Stage 2 removes suspended solids and turbidity. Odour, colour and residual dissolved hydrocarbons are the activated-carbon filter's job (Stage 3), and the hardness salts that leave scale and white spots are the resin softener's (Stage 4). Each stage handles what the one before it cannot.

Where does the backwash water go?

Out through the control valve's waste port to your sludge line or drain, carrying the solids the bed had collected. It is a small volume against what a wash bay consumes, and it is the reason a closed loop still needs a modest freshwater make-up.

The W100 system